Chinese Paddlefish

The Chinese paddlefish had a white underbelly, and its back and head were grey. Its dorsal and anal fins were situated considerably far back on the body. The paddle-like rostrum was narrow and pointed, and was between a quarter and up to a third of total body length. Its eyes were small and round. The tail fin was heterocercal (spine extending into the upper lobe), with the lower lobe being well developed. The skull is more elongate and narrower than that of the American paddlefish, and lacks the sculpturing present on the skull bones of other paddlefish, with the stellate (star-shaped) bones on the rostrum less numerous than those of the American paddlefish. The teeth were small, sharp, canine shaped and inward curling, and became proportionally smaller relative to the jaw during growth, and in mature adults were completely fused into the bone. Compared to Polyodon, the jaws were shorter, and had a proportionately narrower gape, and unlike the American paddlefish, but similar to fossil paddlefish, the upper jaw was not firmly attached to the braincase. Like other paddlefish, the skeleton was largely cartilaginous. …

The Chinese paddlefish was native to the Yangtze (Chang Jiang) River basin and its estuary at the East China Sea. Historically it was also recorded in the Yellow River basin (which is connected to the Yangtze by the Grand Canal) and its estuary at the Yellow Sea. They were also historically found in coastal waters of the East China Sea and the Yellow Sea; occasionally spring tides would bring individuals into the lower reaches of the Qiantang and Yong rivers of Zhejiang province. It primarily inhabited the rivers, particularly in the case of the Yangtze the relatively more prey-rich lower-middle reaches as opposed to the relatively food-poor upper reaches, but sometimes travelled into large lakes. During fall and winter, breeding-age adults migrated from the rest of the Yangtze river system to the lower Jinsha River (a name given to the upper part of the Yangtze) in the section of the river around the city of Yibin in southern Sichuan, to congregate for spawning, which occurred in spring of the following year, from mid-March to early April. Males and females are suggested to have reached sexual maturity and began spawning at 5 and 6 years of age respectively, with spawning males being reported as approximately 5–10 years of age, while spawning females were generally 6 to 16 years of age. …

The species was first named as a species of Polyodon (the genus of the American paddlefish) by Eduard von Martens in 1862. It was placed into a separate, monotypic genus by Albert Günther in 1873. The species was also given a different name, Spatularia angustifolium by Johann Jakob Kaup also in 1862, but this is considered a junior synonym of P. gladius. Paddlefish (Polyodontidae) are one of two living families of Acipenseriformes alongside sturgeons (Acipenseridae). The oldest records of Acipenseriformes date to the Early Jurassic, over 190 million years ago. The oldest paddlefish fossil is that of Protopsephurus from the Early Cretaceous of China, dating to around 120 million years ago. The oldest representatives of the genus containing the American paddlefish, Polyodon date to around 65 million years ago, from the beginning of the Paleocene. Various molecular clock estimates have been given for the age of the divergence between the American and Chinese paddlefish, including 68 million years ago 72 million years ago, and 100 million years ago, all dating to the middle to Upper Cretaceous.

Relationships of recent and fossil paddlefish genera, after Grande et al. (2002).